BACKGROUND

To evaluate the role of in utero exposure to metronidazole (a carcinogen in some animal models) and the risk of subsequent cancer, the authors conducted a retrospective cohort study of childhood cancer.

METHODS

The cohort included 328,846 children younger than 5 years born to women enrolled in Tennessee Medicaid at any time between the last menstrual period (LMP) and the date of delivery.

The cohort was identified by linking files of Tennessee Medicaid mothers ages 15-44 years and children and the children's birth and death certificates for the period lanuary 1,1975 through December 31,1992.

Exposure data were obtained from Medicaid pharmacy records and exposure was defined as filling a metronidazole prescription that had at least a day's supply between the 30 days prior to the LMP and the date of delivery.

Study cases were cohort children diagnosed with a first primary cancer before age 5 years, identified by linking the cohort with a statewide childhood cancer database for the study period.

RESULTS

Cohort members contributed 1,172,696 person-years of follow-up for analysis, with children exposed (8.1%) and not exposed (91.9%) in utero to metronidazole contributing 79,716 and 1,092,980 person-years, respectively.

Of 952 children younger than 5 years in the statewide cancer database, 175 met study eligibility criteria.

Of these, 42 had leukemia, 30 had central nervous system (CNS) tumors, 28 had neuroblastoma, and 75 had other cancers. (...)